Mark Conner
As some of you know
Wednesday, January 19, 2022, 18:13

I enjoy shooting a few rock chucks in the Spring when time allows. In the past, I have always used either my Coyote Classic in 218 Mashburn Bee or 300 GNR in a rechambered 30 carbine. After picking up an older Contender frame, Gary built a 7 GNR barrel for me that I was able to use last season.

In the 7 as in the 218 and the 300 I wanted to shoot cast for the chucks. My BIL, who has a 7 TC/U, has a couple moulds he got from one of Gary's estate sales so I borrowed the Lyman 287346 from him and used it last year and it served me well.

But I really wanted a flat nosed hollow point design, so I contacted Al at NOE and after a 5 month wait (everybody is behind) a 4 cavity 288135 with h.p. pins showed up.

Bullets were cast and load testing began. I started with IMR 4064 and a good load was finally found but it was reduced enough that the powder became pretty position sensitive, I could get good groups but I had to raise the muzzle vertically then lower it slowly, without doing this the load shot vertical strings of 3" at 65 yards. Not wanting to do this each time I shot I figured I had a couple of options... (1) Switch powder (2) or try a filler.

I tried the switch powders first, going with 2400 an ok load was found, but not having much 2400 on hand and it just being an ok load I went to the other end of the scale and tried IMR 4350. It did not shoot any better than 4064 and I used a lot more of it and not getting any better groups it was not really worth it to me. So bring on the filler. I was very leery to try this with the stories of ringed barrels. I thought I understood the process so I went back to my 4064 load that shot so well with muzzle elevation and put .8 of a grain of dacron filling in the space between powder and bullet, not packing it tightly but making sure it was well on the powder and filling all the space in the case to the bullets base. The addition of the dacron really cleaned up the powder burn and made good consecutive groups, but ringing a barrel was always on my mind.

Today I decided to try some IMR 3031, I have a very good load with this powder and Nosler 120 gr. BT. I started with 2 grs. less than the 4064 load, expecting about the same results I was quite pleased when I walked up to the target and saw this, and I don't have to worry about the dreaded barrel ring.

About 65 yards, sitting on the cold wet ground shooting off cross sticks. I know if there is a better load I could not shoot it any better. My search for a cast bullet rock chuck load is finished.